Reciprocating electromagnetic motor



April 19, 1955 J. w. DICKEY 2,706,795

RECIPROCATING ELECTROMAGNETIC MOTOR Filed Aug. 25, 1952 2 Sheets-Sheet l I N VEN TOR. WITNESS (/Mn/MZ) gm. 975m: w

A TTORNE Y April 19, 1955 J. w. DICKEY 2,706,795

RECIPROCATING ELECTROMAGNETIC MOTOR Filed Aug. 25, 1952 2 Sheets-Sheet 2 a 65 a7 2 0 N :717

31 g l I: 36 s w 29 flz/ 1a IN V EN TOR.

A TORNE Y United States Patent RECIPROCATING ELECTROMAGNETIC MOTOR John W. Dickey, Newfield, N. Y., assignor to Bendix Aviation Corporation, a corporation of Delaware Application August 25, 1952, Serial No. 306,184

4 Claims. (Cl. 310-18) The present invention relates to a reciprocating electromagnetic motor and more particularly to an electromagnetic pump of the type used for supplying fuel to internal combustion engines.

It is an object of the present invention to provide a novel electromagnetic motor which is operable by either alternating current or direct current, and is indifierent to the direction of flow of the direct current.

It is another object to provide such a device in which the means for controlling the actuation of the electromagnet to cause reciprocation of the pump piston is a simple, well-balanced construction which is economical to construct and assemble.

It is another object to provide such a device in which the controlling means comprises a small permanent magnet which actuates an electrical contact by an oscillatory movement; and in which the operation is analogous to a toggle system providing a comparatively wide latitude of dimensions and adjustments without impairing the reliability and efficiency of the operation.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing, in which:

Fig. l is a vertical substantially mid-sectional view of an electromagnetic pump constituting a preferred embodiment of the invention;

Fig. 2 is a section taken substantially on the line 22 of Fig. 1; and

Fig. 3 is a view similar to Fig. 2 showing the position and flux circuit of the control magnet when the piston is drawn out of its flux zone.

In Fig. 1 of the drawing there is illustrated a nonmagnetic cylinder 1 in which a hollow magnetic piston 2 is slidably mounted. A spring 3 normally holds the piston 2 in its upper position against a butter spring 4 as illustrated, and means for drawing the piston downward is provided comprising an electromagnet 5 surrounding the cylinder 1 and having circular pole pieces 6 and 7 which are fixedly mounted in a cylindrical casing 8 of magnetic material.

Means for periodically energizing the electromagnet 5 to cause reciprocation of the piston 2 is provided comprising a battery 9 which is grounded at 11 and is connected through a switch 12 and lead 13 to one terminal 14 of the electromagnet. The opposite terminal 15 of the electromagnet is connected by a lead 16 to a contact 17 which is fixedly mounted on the pole piece 7 while being insulated therefrom as indicated at 18. A movable contact 19 is mounted on a spring blade 21 carried by a cradle 22 of non-magnetic conductive material, which cradle is mounted on the pole piece 7 as indicated at 23 for pivotal movement to bring the contact 19 into and out of engagement with the fixed contact 17. The cradle 22 is grounded at 24 to complete the electrical circuit.

A small permanent magnet 25 is mounted in the upper end of the cradle 22, and as best shown in Fig. 2, conforms approximately to the exterior of the cylinder 1 and moves toward and from said cylinder as the cradle swings about its axis. The magnet 25 is so magnetized that its lines of flux are in planes perpendicular to the axis of the cylinder 1. In other words, when the magnet is in engagement with the cylinder, it partially stirrounds or embraces the cylinder, and the fiux between the poles passes through the cylinder as shown in Fig. 2. A portion of the flux of the magnet also traverses the adjacent portion of the magnetic casing 8, which thus ice provides a parallel path for the flux as shown in Fig. 3, the relative density of the flux in the two parallel paths depending upon the relative sizes of the air gaps in the two paths.

When the piston 2 is near the upper end of its stroke, it enters the zone of flux of the magnet 25 and provides a comparatively low reluctance path for said flux. The magnet is consequently strongly attracted toward the piston and swings the cradle 22 around its pivot 23, bringing contact 19 into engagement with contact 17 prior to engagement of the magnet with the cylinder 1. The consequent energization of the electromagnet 5 draws the piston 2 downward against the compression of the spring 3 until the piston leaves the zone of influence of magnet 25, greatly increasing the reluctance of the magnetic path through the cylinder 1. The major portion of the flux of the magnet is thus caused to traverse the parallel path through the adjacent portion of the casing 8, whereby the magnet is attracted toward the casing, swinging the cradle 22 in a clockwise direction as viewed in Fig. 1, and moving the contact 19 out of engagement with contact 17. The clockwise movement of the cradle is limited by an abutment 26 formed on the cradle which is arranged to engage a non-magnetic partition member 20 and thereby maintain a sufficient air gap between the magnet and casing to ensure that the magnet will be pulled back against cylinder 1 when the piston 2 returns to its upper position.

The pole piece 7 is provided with a notch or cutaway portion 27 providing clearance for an arm 28 of the cradle which carries a counter-weight 29 on its lower end so dimensioned and arranged as to bring the cradle assembly into substantially neutral equilibrium around its pivot 23.

The piston 2 carries a check valve 31 at its lower end, and a second check valve 32 is mounted in a cup member 33 attached to the lower pole piece 6, whereby reciprocation of the piston 2 causes liquid to be drawn from the inlet chamber 34 of the casing and discharged into the outlet chamber 35.

It will be readily appreciated that the provision of the two parallel flux paths for the magnet 25, each having variable air gaps, provides an arrangement which is similar in its action to a toggle in that the movement of the cradle caused by the predominance of the flux in one path or the other, takes place positively and energetically. It has been found that with this arrangement it is unnecessary to work to the customary close tolerances required in devices of this general character, and that smaller and accordingly less expensive magnets are adequate to ensure reliable operation.

In view of the fact that the polarity of the control magnet 25 is transverse to the axis of the electromagnet 5, it is immaterial to the operation of the control magr net whether the upper end of the piston becomes a north pole or a south pole when the electromagnet 5 is energized. It makes no difference therefore which pole of the battery 9 is grounded, and it becomes unnessary to furnish separate models of pump for the reverse battery connections. In fact, it has been found that pumps constructed as herein disclosed operate quietly and eifectively on 60-cycle alternating current without overheating.

Although but one embodiment of the invention has been shown and described in detail, it will be understood that other embodiments are possible and changes may be made in the design and arrangement of the parts without departing from the spirit of the invention.

I claim:

1. In an electromagnetic reciprocating motor, a hollow cylinder of non-magnetic material, a piston of magnetizable material slidably fitted in thecylinder, a spring urging the piston toward one end of the cylinder, an electromagnet surrounding the cylinder and piston so positioned that when energized it moves the piston against the force of the spring, a casing of magnetizable material enclosing the cylinder and electromagnet, and means for controlling the energization of the electromagnet to cause reciprocation of the piston comprising a cradle of non-magnetic material pivoted on an axis located in a plane normal to the axis of the cylinder, a permanent magnet mounted on the cradle with its polar axis parallel to the pivotal axis of thecradle, for swinging movementbetween the cylinder and the casing at a location adjacent the end of the piston when the piston has completed its discharge stroke; said magnet having two parallel flux paths, one of which includes the piston when the piston is at the end of its discharge stroke, and the other of which includes the adjacent portion of the casing; and means for maintaining an air gap in the flux path through the casing to make its reluctance substantially greater than the reluctance of the fiux path through the piston when the piston is in the zone of influence of the magnet; a fixed contact, and a cooperating contact on the cradle engaging the fixed contact responsive to movement of the permanent magnet toward said cylinder, and separated therefrom by movement of said magnet toward the inner surface of the casing.

2. An electromagnetic motor as set forth in claim 1 in which one face of the permanent magnet conforms approximately to the adjacent surface of the cylinder, and including further a non-magnetic abutment limiting movement of said magnet toward the casing.

3. An electromagnetic motor as set forth in claim 1 including further an annular plate surrounding the cylinder and locating it coaxially in the casing, the pivot for the bracket being fixedly mounted on said plate.

4. An electromagnetic motor as set forth in claim 3 in which the annular plate has a peripheral notch, and the cradle has an arm depending through said notch, and a weight on said arm substantially balancing the cradle about its pivot.

References Cited in the file of this patent UNITED STATES PATENTS 2,472,067 Dickey June 7, 1949 2,503,089 Binford Apr. 4, 1950 2,590,680 Campbell Mar. 25, 1952 

